The objectives of the investigation outlined in this proposal is to learn more about aging of eggs, specifically how senescence affects structural and functional apsects of the ovum and its ability to undergo processes of fertizilation. In order to determine the effects of aging, ova will be cultured for varying lengths of time in vitro or obtained from females at various intervals after ovulation. Aging ova will be examine ultrastructurally. Cytochemical investigations involving the localization of various macromolecules, e.g., carbohydrates and enzymes (acid and alkaline phosphastases, nucleosides triphosphatase and beta-glucuronidase) will be carried out. Efforts will be made to localize these enzyme activities in unaged eggs and then determine whether or not they change with senescence. The functional capabilities of aged eggs will be examined by comparing the uptake and incorporaton of tritiated amino acids in aged and unaged ova. In order to establish what effect aging of eggs has on events of fertilization, ova, aged in vivo and in vitro, will be inseminated in vitro. At periodic intervals during fertilization aged ova will be analyzed ultrastructurally and cytochemically and compared with unaged inseminated ova. Analysis of protein and DNA synthesis will also be carried out with fertilized ova and compared with inseminated unaged eggs. These studies will provide us with a better understanding of the mechanisms concerning post-ovulatory overripeness of eggs. Such information is important to our general knowledge of nucleo-cytoplasmic interactions and development and applicable to areas involving the study of conception, contraception, reproductive wastage and congential anomalies in man.